The invention relates generally to a surface-treating apparatus for agitatable material, and more particularly to an improved conveyor trough of an apparatus for galvanically depositing aluminum from an aprotic, oxygen-free and anhydrous aluminum organic electrolytic solution.
It is known that the life span of metallic components can be extended by surface finishing the metallic components. New applications for these surface finished components may be found as well. For example, light metal and ferrous material coatings effectively protect relatively non-precious metals whose surfaces can corrode under the effects of the atmosphere. By using an appropriate pretreatment, the components are given a polished surface free of any unwanted surface film. The metallic coating may also be supplemented by a secondary treatment.
During galvanic treatment, the agitatable small parts must be held together so that the parts make electrical contact with each other. However, the agitatable material to be treated also needs to be sufficiently spread out so that the metallic deposition can be performed over as great a surface area as possible. By satisfying this requirement, an optimally uniform current density is provided on all the parts as well. A further important prerequisite for achieving perfect metal platings with a uniform layer thickness is that the material must be thoroughly mixed during the galvanic treatment. The known devices for electroplating are equipped with conveyors for transporting the agitatable material through an electrolytic solution. A continuous or periodic admission and removal of the material is accomplished via corresponding admission and exit sluices. An additional requirement is that, the agitation, mixing, and transport of the material through the electrolyte should be carried out so that the material is treated gently and so that sensitive parts are not mechanically damaged during galvanic treatment.
These above-mentioned requirements are not only significant in regard to electroplating, such as in mass electrolytic surface plating. These requirements are also significant in regard to the electrochemical surface treatment of agitatable material in liquids, such as during electrolytic degreasing in alkaline baths as well as during electrolytic pickling or electrolytic polishing. During electrolytic surface treatment, the agitatable material is wired either as a cathode or as an anode. For example, the circuit arrangement is such that the agitatable material acts as an anode during electrolytic polishing, but during the deposition of aluminum the agitatable material is preferably wired to act as a cathode.
An apparatus suitable for mass electroplating, particularly for the galvanic deposition of aluminum, is known in the art. This known apparatus has a vibrating conveyor with horizontal and vertical vibrating components to transport the agitatable material through the treatment bath. This apparatus contains an oxygen-free and anhydrous electrolytic solution having an inner surface covered by an inert gas. The admission of air and moisture into the device must be prevented. For this reason, gas, liquid or vacuum sluices are provided to load and remove the agitatable material that is to be processed. By utilizing inertial force, the vibrating conveyor transports the agitatable material along a fixed conveying route that is either horizontal or inclined. Vibrators having a skew effect or tilted guide levers, for example, may serve as the driving mechanisms. These types of driving mechanisms produce vibrations such that the material is periodically lifted off the support, thus undergoing a series of microprojectile type motions. As a result, the material is transported in the direction of conveyance. In addition, gravity conveyors in the form of downspouts may be provided. Such gravity conveyors only require a relatively small motive force to operate and they allow the gentle conveyance of the agitatable material. The result obtained is a very effective movement of the material as well as good electrolytic exchange and uniform current absorption over the entire active surface of the material that is now spread out.
The apparatus for surface-treating agitatable material disclosed in U.S. Pat. No. 3,826,355 includes a conveyor trough which is angularly disposed in only one direction and has a sawtoothed floor. The agitatable material executes projectile motion with an upward component. To accomplish this motion, a rocking driving mechanism is provided for the conveyor trough. In this particular embodiment, the agitatable material can be lifted-up from the conveyor trough while it is in motion. Accordingly, the degree of contact is minimal.
In view of the prior art, there is a need to simplify and improve the known devices for surface-treating agitatable material. More particularly, there is a need to improve the intermixing of the material, to increase the spectrum of materials to be deposited and, to reduce the overall space that is required.